St. George's Castle sits at the junction of three colliding historical currents. Ali Pasha Tepelena was building a personal empire within the Ottoman Empire, using European expertise to fortify his positions against European rivals — specifically Russian troops still stationed on the nearby island of Lefkada after the wars of the 1790s. De Vaudoncourt was one of the many French officers whose careers had been scattered across Europe and the Near East by the Napoleonic upheaval. The Greek stonemasons who actually built the thing had no stake in any of this — they were simply compelled. The fort was built to defend the narrow water channel at the mouth of the Ambracian Gulf, the passage between the Ionian Sea and what the source material here calls the Gulf of Arta. Whoever held Preveza held this channel, and whoever held this channel controlled access to the protected waters beyond.

The castle's design reflects the military engineering conventions of the Napoleonic era. Its enclosure is protected by high polygonal bastions — the polygonal trace, as engineers called it, was standard for the period, designed to eliminate the blind spots of older square or circular fortifications. The outer walls of the enceinte were set at a slight angle to better deflect artillery fire, a detail that looks subtle from outside but represents a mature understanding of ballistic physics. Within a few years of its construction, the fort changed names twice. The Ottomans initially called it one name, then renamed it the 'green castle' (after the figure of Khidr, associated with the color green in Islamic tradition), and finally 'barracks castle.' The name St. George's Castle came only after the Greek liberation in 1912.

Most fortifications from the Napoleonic era have decayed into picturesque ruins. St. George's Castle instead kept being used. The Greek military adapted it into the twentieth century, which meant modifications: battery platforms were excavated, bastions were pierced to create casemates with better protection against modern weapons. The service buildings inside the enclosure are entirely twentieth-century in construction. Only one original element survives — a small masonry building that leads down to the powder magazine, preserving a direct architectural link to 1807. The main entrance at the north-eastern corner of the enclosure still faces the town center, as it did when the fort was first built. Historical photographs — some taken by the Swiss photographer Frédéric Boissonnas in May 1913, just months after Greek forces entered Preveza — show a guardhouse above the entrance that has since been lost.

St. George's Castle is not a ruined monument. It survives as a functional structure, its high walls still enclosing the southern end of the city, its bastions still projecting at careful angles toward the channel. To walk around its exterior is to read the accretion of events it has witnessed: the forced labor of Greek workers under an Ottoman warlord; the strategic thinking of a French engineer who couldn't get credit for his own design; the Greek military's pragmatic adaptations over more than a century of service; the gradual retirement into civic memory that gives old forts their second lives. The name St. George was given to it after liberation, replacing an Ottoman designation with a Greek saint. Even the renaming is part of the story — a small act of reclamation in a city that has been renamed, refounded, and reconquered more times than most.